A 1,800-year-old silver amulet discovered in a burial in Germany is the oldest evidence of Christianity north of the Alps, according to a new study.

Researchers made the discovery by digitally unrolling a tiny scroll inside the amulet, which revealed an unusual Latin inscription. The finding may upend historians' understanding of how Christianity was practiced in the early Roman Empire.

Measuring just 1.4 inches (3.5 centimeters) long, the amulet contains a wafer-thin sheet of silver foil that's rolled up tightly. Archaeologists discovered it in the grave of a man who died between A.D. 230 and 270 and was buried in a cemetery on the outskirts of Frankfurt. The man likely wore the amulet on a cord around his neck, as it was found just below his chin.

The purpose of these amulets, also known as phylacteries, "was to protect or heal their owners from a range of misfortunes, such as illnesses, bodily aches, infertility, or even demonic forces," Tine Rassalle, an independent biblical archaeologist who was not involved in the study, told Live Science in an email. "In an era without advanced medical knowledge, such items were vital sources of comfort and security for you and your loved ones."

The location of the artifact's discovery is rare, she added.